In recent, an indoor location recognition system has been utilized in numerous areas such navigation, warehouse management, patient management in hospitals, material management in factories, and others. Further, since the indoor location recognition system is possible to seek various applications, many researchers and developers have developed a variety of techniques in order to recognize an accurate indoor location.
Typical methods for recognizing an indoor location can be largely classified into a method based on triangulation using a physical distance and angel such as TDoA (Time Difference of Arrival), AoA (Angle of Arrival), ToA (Time of Arrival), etc. and a method based on the map to database the features of radio signals that characterize the locations. Moreover, the wireless devices used to measure the distance, angle, strength of the radio signals required for the position recognition of the indoor space mainly utilize a radio system such as Bluetooth, WLAN (Wireless LAN), Zigbee, UWB (Ultra-Wide Band), RF, Ultrasonic, Mobile (GSM/CDMA), and the like.
Although the method using a UWB device exhibits excellent accuracy, it has problems that it requires equipment that is specially designed for the indoor location recognition and the cost to build infrastructure to provide an indoor location recognition service to the public. In the case of using a mobile (e.g., GSM/CDMA) device for which infrastructure is well built, accuracy in the indoor location recognition is poor because of the nature that the base stations are not disposed densely. In a case of a method that utilizes Bluetooth, Zigbee, RF, Ultrasonic, or WLAN device, it is possible to develop a module for the indoor location recognition with a proper level (1˜10 m or less) at a low cost. Therefore, this method is widely used in recognizing the indoor location.
In particular, by virtue of the development of mobile computing technology, an infrastructure of WLAN (IEEE 802.11) is also built well in an indoor space, similarly to the infrastructure of the mobile device. Therefore, in a worldwide enterprise and laboratories such as Microsoft, Nokia, Ekahau, etc. have continued to develop the technology relevant to the indoor location recognition. However, while the technology relevant to the indoor location recognition has been developed up to now, it is not enough to be commonly used in the general public. The reason is that the technology basically not only requires equipment that is specifically designed, but also needs to create in advance an RSSI map in which a database of the radio signal strength indication (RSSI) is built. Even if an indoor location recognition service provider creates the RSSI map in advance by investing the huge amount of money, the uncertainty depending on the dynamic environment due to the nature of the radio signals becomes a major obstacle when the technique is commonly used in real.
Accordingly, it is necessary to provide a method of creating an accurate indoor RSSI map that can be commonly used at low cost, and there is a need for ensuring that the RSSI map can be utilized for an accurate indoor location recognition by providing it to general users.